Certain polyesteramides are high oxygen barrier materials useful in many food and beverage packaging applications. Very often, polyesteramides are used to form a barrier layer in multilayered containers produced by either coinjection or coextrusion processes with other polymers such as polyesters, in particular, poly(ethylene terephthalate) (PET). Polyesteramides have good adhesion to PET in these applications, but the melt viscosity match is very poor and often results in poor distribution of the barrier layer in the coinjected part on the coextruded sheet. Also, polyesteramides have glass transition temperatures which make it extremely difficult to dry.
It has been found that blends of selected polyesters with selected polyesteramides can be used to provide barrier layer materials that have improved drying properties and an improved melt viscosity match with PET resulting in improved processing for coinjection and coextrusion operations. Also, the improvement in processing has been found to be related to the method of making the polyesteramide/polyester melt blends. In addition, it has been found that blends of certain polyesteramides with glycol-modified PET can be coinjected and blow molded at conditions which will show improved clarity compared to PET/polyesteramide blends.
Of interest in connection with this invention is U.S. Pat. No. 4,501,879 which describes polyesteramides useful in this invention.